1 // SPDX-License-Identifier: GPL-2.0 2 3 #define _GNU_SOURCE 4 #include <errno.h> 5 #include <fcntl.h> 6 #include <pthread.h> 7 #include <sched.h> 8 #include <stdbool.h> 9 #include <stdio.h> 10 #include <stdlib.h> 11 #include <string.h> 12 #include <sys/fsuid.h> 13 #include <sys/ioctl.h> 14 #include <sys/mount.h> 15 #include <sys/socket.h> 16 #include <sys/stat.h> 17 #include <sys/sysinfo.h> 18 #include <sys/types.h> 19 #include <sys/wait.h> 20 #include <unistd.h> 21 #include <linux/android/binder.h> 22 #include <linux/android/binderfs.h> 23 24 #include "../../kselftest_harness.h" 25 26 #define DEFAULT_THREADS 4 27 28 #define PTR_TO_INT(p) ((int)((intptr_t)(p))) 29 #define INT_TO_PTR(u) ((void *)((intptr_t)(u))) 30 31 #define close_prot_errno_disarm(fd) \ 32 if (fd >= 0) { \ 33 int _e_ = errno; \ 34 close(fd); \ 35 errno = _e_; \ 36 fd = -EBADF; \ 37 } 38 39 static void change_mountns(struct __test_metadata *_metadata) 40 { 41 int ret; 42 43 ret = unshare(CLONE_NEWNS); 44 ASSERT_EQ(ret, 0) { 45 TH_LOG("%s - Failed to unshare mount namespace", 46 strerror(errno)); 47 } 48 49 ret = mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, 0); 50 ASSERT_EQ(ret, 0) { 51 TH_LOG("%s - Failed to mount / as private", 52 strerror(errno)); 53 } 54 } 55 56 static int __do_binderfs_test(struct __test_metadata *_metadata) 57 { 58 int fd, ret, saved_errno, result = 1; 59 size_t len; 60 ssize_t wret; 61 struct binderfs_device device = { 0 }; 62 struct binder_version version = { 0 }; 63 char binderfs_mntpt[] = P_tmpdir "/binderfs_XXXXXX", 64 device_path[sizeof(P_tmpdir "/binderfs_XXXXXX/") + BINDERFS_MAX_NAME]; 65 static const char * const binder_features[] = { 66 "oneway_spam_detection", 67 "extended_error", 68 }; 69 70 change_mountns(_metadata); 71 72 EXPECT_NE(mkdtemp(binderfs_mntpt), NULL) { 73 TH_LOG("%s - Failed to create binderfs mountpoint", 74 strerror(errno)); 75 goto out; 76 } 77 78 ret = mount(NULL, binderfs_mntpt, "binder", 0, 0); 79 EXPECT_EQ(ret, 0) { 80 if (errno == ENODEV) 81 SKIP(goto out, "binderfs missing"); 82 TH_LOG("%s - Failed to mount binderfs", strerror(errno)); 83 goto rmdir; 84 } 85 86 /* success: binderfs mounted */ 87 88 memcpy(device.name, "my-binder", strlen("my-binder")); 89 90 snprintf(device_path, sizeof(device_path), "%s/binder-control", binderfs_mntpt); 91 fd = open(device_path, O_RDONLY | O_CLOEXEC); 92 EXPECT_GE(fd, 0) { 93 TH_LOG("%s - Failed to open binder-control device", 94 strerror(errno)); 95 goto umount; 96 } 97 98 ret = ioctl(fd, BINDER_CTL_ADD, &device); 99 saved_errno = errno; 100 close(fd); 101 errno = saved_errno; 102 EXPECT_GE(ret, 0) { 103 TH_LOG("%s - Failed to allocate new binder device", 104 strerror(errno)); 105 goto umount; 106 } 107 108 TH_LOG("Allocated new binder device with major %d, minor %d, and name %s", 109 device.major, device.minor, device.name); 110 111 /* success: binder device allocation */ 112 113 snprintf(device_path, sizeof(device_path), "%s/my-binder", binderfs_mntpt); 114 fd = open(device_path, O_CLOEXEC | O_RDONLY); 115 EXPECT_GE(fd, 0) { 116 TH_LOG("%s - Failed to open my-binder device", 117 strerror(errno)); 118 goto umount; 119 } 120 121 ret = ioctl(fd, BINDER_VERSION, &version); 122 saved_errno = errno; 123 close(fd); 124 errno = saved_errno; 125 EXPECT_GE(ret, 0) { 126 TH_LOG("%s - Failed to open perform BINDER_VERSION request", 127 strerror(errno)); 128 goto umount; 129 } 130 131 TH_LOG("Detected binder version: %d", version.protocol_version); 132 133 /* success: binder transaction with binderfs binder device */ 134 135 ret = unlink(device_path); 136 EXPECT_EQ(ret, 0) { 137 TH_LOG("%s - Failed to delete binder device", 138 strerror(errno)); 139 goto umount; 140 } 141 142 /* success: binder device removal */ 143 144 snprintf(device_path, sizeof(device_path), "%s/binder-control", binderfs_mntpt); 145 ret = unlink(device_path); 146 EXPECT_NE(ret, 0) { 147 TH_LOG("Managed to delete binder-control device"); 148 goto umount; 149 } 150 EXPECT_EQ(errno, EPERM) { 151 TH_LOG("%s - Failed to delete binder-control device but exited with unexpected error code", 152 strerror(errno)); 153 goto umount; 154 } 155 156 /* success: binder-control device removal failed as expected */ 157 158 for (int i = 0; i < ARRAY_SIZE(binder_features); i++) { 159 snprintf(device_path, sizeof(device_path), "%s/features/%s", 160 binderfs_mntpt, binder_features[i]); 161 fd = open(device_path, O_CLOEXEC | O_RDONLY); 162 EXPECT_GE(fd, 0) { 163 TH_LOG("%s - Failed to open binder feature: %s", 164 strerror(errno), binder_features[i]); 165 goto umount; 166 } 167 close(fd); 168 } 169 170 /* success: binder feature files found */ 171 result = 0; 172 173 umount: 174 ret = umount2(binderfs_mntpt, MNT_DETACH); 175 EXPECT_EQ(ret, 0) { 176 TH_LOG("%s - Failed to unmount binderfs", strerror(errno)); 177 } 178 rmdir: 179 ret = rmdir(binderfs_mntpt); 180 EXPECT_EQ(ret, 0) { 181 TH_LOG("%s - Failed to rmdir binderfs mount", strerror(errno)); 182 } 183 out: 184 return result; 185 } 186 187 static int wait_for_pid(pid_t pid) 188 { 189 int status, ret; 190 191 again: 192 ret = waitpid(pid, &status, 0); 193 if (ret == -1) { 194 if (errno == EINTR) 195 goto again; 196 197 return -1; 198 } 199 200 if (!WIFEXITED(status)) 201 return -1; 202 203 return WEXITSTATUS(status); 204 } 205 206 static int setid_userns_root(void) 207 { 208 if (setuid(0)) 209 return -1; 210 if (setgid(0)) 211 return -1; 212 213 setfsuid(0); 214 setfsgid(0); 215 216 return 0; 217 } 218 219 enum idmap_type { 220 UID_MAP, 221 GID_MAP, 222 }; 223 224 static ssize_t read_nointr(int fd, void *buf, size_t count) 225 { 226 ssize_t ret; 227 again: 228 ret = read(fd, buf, count); 229 if (ret < 0 && errno == EINTR) 230 goto again; 231 232 return ret; 233 } 234 235 static ssize_t write_nointr(int fd, const void *buf, size_t count) 236 { 237 ssize_t ret; 238 again: 239 ret = write(fd, buf, count); 240 if (ret < 0 && errno == EINTR) 241 goto again; 242 243 return ret; 244 } 245 246 static int write_id_mapping(enum idmap_type type, pid_t pid, const char *buf, 247 size_t buf_size) 248 { 249 int fd; 250 int ret; 251 char path[4096]; 252 253 if (type == GID_MAP) { 254 int setgroups_fd; 255 256 snprintf(path, sizeof(path), "/proc/%d/setgroups", pid); 257 setgroups_fd = open(path, O_WRONLY | O_CLOEXEC | O_NOFOLLOW); 258 if (setgroups_fd < 0 && errno != ENOENT) 259 return -1; 260 261 if (setgroups_fd >= 0) { 262 ret = write_nointr(setgroups_fd, "deny", sizeof("deny") - 1); 263 close_prot_errno_disarm(setgroups_fd); 264 if (ret != sizeof("deny") - 1) 265 return -1; 266 } 267 } 268 269 switch (type) { 270 case UID_MAP: 271 ret = snprintf(path, sizeof(path), "/proc/%d/uid_map", pid); 272 break; 273 case GID_MAP: 274 ret = snprintf(path, sizeof(path), "/proc/%d/gid_map", pid); 275 break; 276 default: 277 return -1; 278 } 279 if (ret < 0 || ret >= sizeof(path)) 280 return -E2BIG; 281 282 fd = open(path, O_WRONLY | O_CLOEXEC | O_NOFOLLOW); 283 if (fd < 0) 284 return -1; 285 286 ret = write_nointr(fd, buf, buf_size); 287 close_prot_errno_disarm(fd); 288 if (ret != buf_size) 289 return -1; 290 291 return 0; 292 } 293 294 static void change_userns(struct __test_metadata *_metadata, int syncfds[2]) 295 { 296 int ret; 297 char buf; 298 299 close_prot_errno_disarm(syncfds[1]); 300 301 ret = unshare(CLONE_NEWUSER); 302 ASSERT_EQ(ret, 0) { 303 TH_LOG("%s - Failed to unshare user namespace", 304 strerror(errno)); 305 } 306 307 ret = write_nointr(syncfds[0], "1", 1); 308 ASSERT_EQ(ret, 1) { 309 TH_LOG("write_nointr() failed"); 310 } 311 312 ret = read_nointr(syncfds[0], &buf, 1); 313 ASSERT_EQ(ret, 1) { 314 TH_LOG("read_nointr() failed"); 315 } 316 317 close_prot_errno_disarm(syncfds[0]); 318 319 ASSERT_EQ(setid_userns_root(), 0) { 320 TH_LOG("setid_userns_root() failed"); 321 } 322 } 323 324 static void change_idmaps(struct __test_metadata *_metadata, int syncfds[2], pid_t pid) 325 { 326 int ret; 327 char buf; 328 char id_map[4096]; 329 330 close_prot_errno_disarm(syncfds[0]); 331 332 ret = read_nointr(syncfds[1], &buf, 1); 333 ASSERT_EQ(ret, 1) { 334 TH_LOG("read_nointr() failed"); 335 } 336 337 snprintf(id_map, sizeof(id_map), "0 %d 1\n", getuid()); 338 ret = write_id_mapping(UID_MAP, pid, id_map, strlen(id_map)); 339 ASSERT_EQ(ret, 0) { 340 TH_LOG("write_id_mapping(UID_MAP) failed"); 341 } 342 343 snprintf(id_map, sizeof(id_map), "0 %d 1\n", getgid()); 344 ret = write_id_mapping(GID_MAP, pid, id_map, strlen(id_map)); 345 ASSERT_EQ(ret, 0) { 346 TH_LOG("write_id_mapping(GID_MAP) failed"); 347 } 348 349 ret = write_nointr(syncfds[1], "1", 1); 350 ASSERT_EQ(ret, 1) { 351 TH_LOG("write_nointr() failed"); 352 } 353 354 close_prot_errno_disarm(syncfds[1]); 355 } 356 357 struct __test_metadata *_thread_metadata; 358 static void *binder_version_thread(void *data) 359 { 360 struct __test_metadata *_metadata = _thread_metadata; 361 int fd = PTR_TO_INT(data); 362 struct binder_version version = { 0 }; 363 int ret; 364 365 ret = ioctl(fd, BINDER_VERSION, &version); 366 if (ret < 0) 367 TH_LOG("%s - Failed to open perform BINDER_VERSION request\n", 368 strerror(errno)); 369 370 pthread_exit(data); 371 } 372 373 /* 374 * Regression test: 375 * 2669b8b0c798 ("binder: prevent UAF for binderfs devices") 376 * f0fe2c0f050d ("binder: prevent UAF for binderfs devices II") 377 * 211b64e4b5b6 ("binderfs: use refcount for binder control devices too") 378 */ 379 TEST(binderfs_stress) 380 { 381 int fds[1000]; 382 int syncfds[2]; 383 pid_t pid; 384 int fd, ret; 385 size_t len; 386 struct binderfs_device device = { 0 }; 387 char binderfs_mntpt[] = P_tmpdir "/binderfs_XXXXXX", 388 device_path[sizeof(P_tmpdir "/binderfs_XXXXXX/") + BINDERFS_MAX_NAME]; 389 390 ret = socketpair(PF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, syncfds); 391 ASSERT_EQ(ret, 0) { 392 TH_LOG("%s - Failed to create socket pair", strerror(errno)); 393 } 394 395 pid = fork(); 396 ASSERT_GE(pid, 0) { 397 TH_LOG("%s - Failed to fork", strerror(errno)); 398 close_prot_errno_disarm(syncfds[0]); 399 close_prot_errno_disarm(syncfds[1]); 400 } 401 402 if (pid == 0) { 403 int i, j, k, nthreads; 404 pthread_attr_t attr; 405 pthread_t threads[DEFAULT_THREADS]; 406 change_userns(_metadata, syncfds); 407 change_mountns(_metadata); 408 409 ASSERT_NE(mkdtemp(binderfs_mntpt), NULL) { 410 TH_LOG("%s - Failed to create binderfs mountpoint", 411 strerror(errno)); 412 } 413 414 ret = mount(NULL, binderfs_mntpt, "binder", 0, 0); 415 ASSERT_EQ(ret, 0) { 416 TH_LOG("%s - Failed to mount binderfs, check if CONFIG_ANDROID_BINDERFS is enabled in the running kernel", 417 strerror(errno)); 418 } 419 420 for (int i = 0; i < ARRAY_SIZE(fds); i++) { 421 422 snprintf(device_path, sizeof(device_path), 423 "%s/binder-control", binderfs_mntpt); 424 fd = open(device_path, O_RDONLY | O_CLOEXEC); 425 ASSERT_GE(fd, 0) { 426 TH_LOG("%s - Failed to open binder-control device", 427 strerror(errno)); 428 } 429 430 memset(&device, 0, sizeof(device)); 431 snprintf(device.name, sizeof(device.name), "%d", i); 432 ret = ioctl(fd, BINDER_CTL_ADD, &device); 433 close_prot_errno_disarm(fd); 434 ASSERT_EQ(ret, 0) { 435 TH_LOG("%s - Failed to allocate new binder device", 436 strerror(errno)); 437 } 438 439 snprintf(device_path, sizeof(device_path), "%s/%d", 440 binderfs_mntpt, i); 441 fds[i] = open(device_path, O_RDONLY | O_CLOEXEC); 442 ASSERT_GE(fds[i], 0) { 443 TH_LOG("%s - Failed to open binder device", strerror(errno)); 444 } 445 } 446 447 ret = umount2(binderfs_mntpt, MNT_DETACH); 448 ASSERT_EQ(ret, 0) { 449 TH_LOG("%s - Failed to unmount binderfs", strerror(errno)); 450 rmdir(binderfs_mntpt); 451 } 452 453 nthreads = get_nprocs_conf(); 454 if (nthreads > DEFAULT_THREADS) 455 nthreads = DEFAULT_THREADS; 456 457 _thread_metadata = _metadata; 458 pthread_attr_init(&attr); 459 for (k = 0; k < ARRAY_SIZE(fds); k++) { 460 for (i = 0; i < nthreads; i++) { 461 ret = pthread_create(&threads[i], &attr, binder_version_thread, INT_TO_PTR(fds[k])); 462 if (ret) { 463 TH_LOG("%s - Failed to create thread %d", 464 strerror(errno), i); 465 break; 466 } 467 } 468 469 for (j = 0; j < i; j++) { 470 void *fdptr = NULL; 471 472 ret = pthread_join(threads[j], &fdptr); 473 if (ret) 474 TH_LOG("%s - Failed to join thread %d for fd %d", 475 strerror(errno), j, PTR_TO_INT(fdptr)); 476 } 477 } 478 pthread_attr_destroy(&attr); 479 480 for (k = 0; k < ARRAY_SIZE(fds); k++) 481 close(fds[k]); 482 483 exit(EXIT_SUCCESS); 484 } 485 486 change_idmaps(_metadata, syncfds, pid); 487 488 ret = wait_for_pid(pid); 489 ASSERT_EQ(ret, 0) { 490 TH_LOG("wait_for_pid() failed"); 491 } 492 } 493 494 TEST(binderfs_test_privileged) 495 { 496 if (geteuid() != 0) 497 SKIP(return, "Tests are not run as root. Skipping privileged tests"); 498 499 if (__do_binderfs_test(_metadata)) 500 SKIP(return, "The Android binderfs filesystem is not available"); 501 } 502 503 TEST(binderfs_test_unprivileged) 504 { 505 int ret; 506 int syncfds[2]; 507 pid_t pid; 508 509 ret = socketpair(PF_LOCAL, SOCK_STREAM | SOCK_CLOEXEC, 0, syncfds); 510 ASSERT_EQ(ret, 0) { 511 TH_LOG("%s - Failed to create socket pair", strerror(errno)); 512 } 513 514 pid = fork(); 515 ASSERT_GE(pid, 0) { 516 close_prot_errno_disarm(syncfds[0]); 517 close_prot_errno_disarm(syncfds[1]); 518 TH_LOG("%s - Failed to fork", strerror(errno)); 519 } 520 521 if (pid == 0) { 522 change_userns(_metadata, syncfds); 523 if (__do_binderfs_test(_metadata)) 524 exit(2); 525 exit(EXIT_SUCCESS); 526 } 527 528 change_idmaps(_metadata, syncfds, pid); 529 530 ret = wait_for_pid(pid); 531 if (ret) { 532 if (ret == 2) 533 SKIP(return, "The Android binderfs filesystem is not available"); 534 ASSERT_EQ(ret, 0) { 535 TH_LOG("wait_for_pid() failed"); 536 } 537 } 538 } 539 540 TEST_HARNESS_MAIN 541